Single blow heading machine with two part header punch



y 1953 R. H. CARLSON 2,832,970 I SINGLE BLOW HEADING MACHINE WITH TWO PART HEADER PUNCH File'd Oct. 4. 1954 5 Sheets-Sheet 1 INVENTOR. RAY H- CARLSON im w ' ATTORNEYS R. H. CARLSON 2,832,970

5 Sheets-Sheet 2 w 7/ W. 3 W 9 2 "w 42 A! /////Mm 5 .4 w m mm 1| l 7 Z 4 5 H H 1. L24 II A 2 1 SINGLE BLOW HEADING MACHINE WITH TWO PART HEADER PUNCH May 6, 1958 Filed Oct. 4, 1954 INVENTOR. RAY H. CARLSON ATTORNEYS y 1958 R. H. CARLSON 2,832,970

SINGLE BLQW HEADING MACHINE WITH TWO PART HEADER PUNCH Filed 001;. 4. 1954 3 Sheets-Sheet 3 RAY H. CARLSON INVENTOR.

United States Patent- SINGLE BLOW HEADING MACHINE WITH TWO PART HEADER PUNCH Raymond H. Carlson, Rockford, Ill., assignor to Camcar Screw & Mfg. Corp., Rockford, 111., a corporation of Illinois Application October 4, 1954, Serial No. 460,224

1 Claims. 01. -11

The present invention relates to cold heading machines and particularly to such machines of the single blow type.

Heretofore, cold heading machines capable of upsetting large masses or volumes of wire stock, that is two diameters and above, have been of the double blow type. It has not been possible, with machines as provided heretofore, to upset such volumes by a single blow machine without producing a high percentage of defective product.

It is a principal object of the present invention to pro.

vide a single blow machine capable of successfully forming headed products of such sizes and shapes that heretofore required a double blow machine. This object is accomplished by providing a new and improved punch unit which may be mounted in a conventional single blow header to greatly expand its range of utility and also enables a greatly increased speed of operation of such single blow header. ticul'arly suitable for use in a laterally fed heading ma chine which still further expands the field of usefulness of the machine. The essential feature of novelty of the present invention resides in the provision of a new punch structure including means for bringing the punch into contact with the die before the cold working step begins and for holding the punch continuously in such contact during the entire cold working step to thus provide a fixed volume matrix cavity into which the metal is cold flowed. Thus, there is no possibility for defective head formation during the cold working step since the metal can flow only into a cavity having the configuration of the final head to be formed.

.A more specific object of the present invention is to provide a cold heading machine, of the type wherein stock is fed laterally between the punch and die by a transfer and severing means, capable of operating at a higher rate of speed than priormachines of such type. Heretofore, a major obstacle to increasing the speed of operation of such machines has been that as the speed increases,.increased difficulty in properly inserting the stock into the punch and die bores is encountered because of the increased magnitude of vibration of the stock due to the higher rate of movement thereof. The machine of the present invention overcomes the above difficulty by being equipped with a punch having the end of the bore opposite the die flared or enlarged to guide the vibrating piece of stock into the punch bore, whereafter, the stock readily enters the die bore.

However, by flaring the end of the punch bore opposite the die, a flashing is produced in the cold working step. It is another object of the present invention to provide a machine operable to bury or recess this flashing within the head of the blank produced, to thus dispose the flashing in a harmless and unobjectionable place. This is accomplished by providing an annular bead on theend of the punch opposite the die arranged to project into the die cavity to form the periphery of a socket, and making the stroke of the pressure pin such that the working end thereof moves below the base of the bead. The

Moreover, the punch unit is par:'

flashing formed between the flared bore end and the pressure pin is thus buried or recessed within a socket formed in the head of the blank being formed.

It is another object of the present invention, to provide a machine of the type under consideration, wherein the die bore has a portion tapering away from the punch in a degree to either form a slight lead or taper on the die end of the piece of stock, orform a distinct and considerable taper on such end, when the piece of stock is forced into the die and within the confines of the tapered die bore walls. Thus, when blanks having lead ends formed thereon are processed by the thread rolling dies, the resulting product is readily inserted in place when utilized. When the tapered blanks are processed by gimlet thread rolling dies, a gimlet point which is properly coaxial with the remainder of the shank is readily accurately formed on the headed blank. An accurately formed gimlet end is of marked importance in the successful and facile use of gimlet end type screws.

Various other objects of the present invention will be apparent from the following description taken in connection with the accompanying drawings, wherein:

Fig. 1 is a view of the essential parts of a cold heading machine embodyingthe concepts of the present invention, the parts being shown in the positions they assume just after the beginning of a cycle of operation of the machine; v

Figs. 2 to 4 show views of the cold heading machine with the parts arranged in intermediate positions;

Fig. 5 shows the parts at the end of the cold working step;

Fig.6 is an enlarged fragmentary sectional view of the end of the punch unit;

Fig. 7 is an enlarged fragmentary view showing the positions of the punch'and pressure pin at the end of the cold working step; and

Fig. 8 is a perspective view of a blank formed by the machine of Figs. 1 through 7.

Referring to the accompanying drawings, the invention will be described with reference to a conventional cold heading machine including a stationary head block or anvil 10 and a reciprocating crosshead including a block 11 carrying a holder 12 in which is held a punch mount 13. A punch back-up wedge 14 is carried by the crosshead in a conventional manner for movement in unison with the crosshead toward and away frornthe anvil 10.

.A die unit 15 is mounted within anvil 10 by means of a holder 16. Unit 15 has a planar face surface and a recess or matrix cavity having a configuration corresponding to that of the headed blank to be formed. The cavity comprises a head defining portion 17 and an axial shank defining bore 18 communicating with the bottom of the head cavity 17, the bore 18 being tapered at the lower end as indicated at 19 where the bore 18 merges with a reduced diameter. axial passage and within which passage the knockout pin 23 is slidably arranged. The knockout pin 23 and operating means therefor are of conventional design and need not be further described. The purpose of the taper-19 atthe end of the shank defining bore 18 is to form a conically tapered or reduced diameter end portion on the end of the workpiece for reasons to appear hereinafter.

The punch unit, forming a part of the present invention, includes an outer sleeve 35 which is rigidly secured in place in the mount 13 by a lock bolt 37. Arranged within the forward end of the sleeve 35 is a cylindrical punch 41 which is axially slidable within the sleeve 35 between the limits provided by the key 42 inserted in the punch and extending into a cooperating keyway slot formed in the sleeve 35 The punch 41 has a diameter considerably greater than the diameter of the cavity 17 with a planar face 43 facing the planar surface of the die block and adapted to match snugly thereagainst during operation of the machine-as will be described hereinafter.

The punch 41 is provided with anaxial'bore within which a drive pin 45 is slidably arranged. The drive pin 45 isattached to or-formed integrally with a head portion 47 which is slidably arranged withinthe sleeve 35. A stiff compression spring 49 is arranged within a cooperating axial recess provided in theend of 'the punch 41 about the pin 45 and normally urges the punch 41 and the head portion 47 apart. The'head portion 47 is provided'with a reduced diameter-end 48 whichis freelyslidable within the cylindrical recess provided-in the adjacent end ofthe punch '41. The-outer end ofthe'drive pin head portion 47 is also provided with a-cylindrical blind bore cooperatively receiving a 'SGCODdhfiff compression spring 53 arranged between the drivepinhetid 47 and a plug 54. The plug is slidzibly arranged within sleeve and is urged by spring 53 against wedge 14. i

With reference to Fig. *1, itwill be *observedthat in the normal or inoperative position of the punch 'unit, the punch 41 isurged to its outward limit position within-the sleeve 35 in which the key'42 abuts the end ofthe cooperating keyway slotprovided in the sleeve side wall. Moreover, attention is directed to the -factthatthe drive pin unit 45,47 is floatingly arranged betweenthepunch 41 and disc 54, and between the two springs 49 and 53.

These two springs areso matched that'the spring 49 is retracted a substantial distance inwardly of the'outer'end of the drive pin bore in'the punch 41. This floating arrangement of the drive pin unit is an-importantfeature of the present invention for reasons which will be pointed out more particularly hereinafter. Certain other details of construction of the punch unit will also be described later.

The present invention is also concerned primarily-with the formation of headed blanks 'whichrequire that the 58 fed through a bore formed in an insert 61fixedlymounted in theholder 16. Thearrangement provided for feeding the wire stock is conventional and is operative to feeda predeterminedlengthof wire, equal to the volume of the blank to be formed, outwardly of the anvil each time the device 57 is retracted to the right, as the parts Upon subsequent movement .of the are shown in Fig. 1. device 57 to the left, the measured length of wire is sheared olf and carried by thedevice 57 into a position in alignment and in register with'the punch and die bores as shown in Fig. l. As the crosshead 11. I2 is then moved toward the anvil 10. the end of the workpiece 60 is inserted into the end of the bore in the punch'41. Relative movement of the end portion of the workpiece 60 into the punch bore 44'is restricted by engagement of the end of the workpiece with the end of the drive pin 45. Continued forward movement ofthe press crosshead will cause the opposite end of the workpiece '60 to be driven into the die bore 18 as indicated in the view of Fig. 2. At this instant, the finger 57 is retracted and continued forward movement .of the press crosshead will cause the workpiece 60 to be firmlyseatedin'the bottom of the cylindrical portion of the die bore 18 as indicated in the view of Fig. 3. Further continued forward movement of the press crosshead will cause the face of the punch 41 to engage snugly against the planar face of the die completely sealing the die cavity about the workpiece.,6 0..before any appreciable deformation of the workpiece occurs. Particular attention is directed to the fact that the drive pin remains relatively stationary during the period of movement of the press crosshead from the position shown in Fig. 3 to that shown in Fig. 4, which is accompanied by compression of .the spring 53 until the disc 54 comes into direct contacting engagement with the upper end of the drive pin head portion 47. The view of Fig. 5

shows the press crosshead 11, 12. in its forward limit oftravel and in which position the drive pin 45 is illustrated as having completely expelled the end portion of the workpiece from the punch bore and the headed blank completely formed.

As previously mentioned, the machine of the present invention is particularly adapted for high speed operation.

A definite problem is confronted in the lateral feeding of a workpiece into the {die 'at high speeds-and particularly because of the extremely short interval of'time during which the workpiece is'heldin the position illustrated-in Fig. 1, between the punch and the die in alignment with the punch and die bores. It ispointed out that as the finger 57 shears the workpiece from the length of Wire stock 58 at high speed, the workpiece vibrates considerably dur'ing the short interval-of time that it is held by thefinger 57. Since the thickness of the finger 57, that is, in the direction longitudinally of theworkpiece, must inherently berelatively narrow, and furthermore because of the fact that the-greater portion of the workpiece must inherently overhang the side of the transfer finger, this vibration of the workpiece continues from the instant of severance until the'end thereof is engaged by the punch unit. If the workpiece were allowedto come to a position of rest at the end of the transfer stroke of the finger 57, which position is shown inFig. 1, the speed of operation of the machine would of necessity have to be relatively slow.

In accordance with the present invention, and in order to facilitate the insertion of the end of the workpiece'into theend portion of the bore 44 of the punch 41, Iprovide a relatively slight curvature to the edge of the opening defining the end of the bore 44 which is illustrated more clearly in the enlarged view of Fig. 6 at 63. I have discovered that with a radius of curvature of the order of .010 inch the end of the workpiece 60 will be guided into the bore 44even though the end of the workpiece 60'may be vibrating considerably at the moment that the punch advances into engagement therewith.

It is apparent that by thus providing a curved edge at the entrance of the punch bore, a flashing between the flared bore end and the drive pin will be produced during the cold working step. It is an important feature of the present invention to bury or recess this flashing below the upper surface of the head of the blank formed. This recession of the flashing is accomplished by providing a continuous annular bead on the lower end of the punch immediately surrounding the bore 44 and in effect defininga continuation or extension of such bore beyond the planar surface 43 of the remainder of the punch face. The height of the bead, indicated at 64, is such that the point of mergence of the curved portion 63 with the cylindrical side walls of the bore 44 is slightly outwardly of the planar face 43 so that the uppermost edge of the flashing produced by the punch will not project above the upper surfaceof the blank head. Inasmuch as the annular head sition indicated. As previously mentioned, the springs49.

and 53 are inbalance with the drive pin head 47 floatingly positioned therebetween and in this position, the end of the drive pin 45 is positioned inwardly of the extremeend of the punch bore 44 so as to expose a substantial .cylindrical portion thereof for cooperatively and freely receiving an end portion of the workpiece 60. As indicated in the view of Fig. 2, the finger 57 remains in contact with the workpiece 60 until such time as the opposite end of the workpiece finds the shank bore 18 in the die 15. As soon as this takes place, the finger 57 is withdrawn and the workpiece is driven into the die bore until the end of the workpiece reaches the taperedlportion 19 of the die. Only the pressure of the spring 53 is applied through the drive pin 45 upon the workpiece during this phase of the operation which is highly important to enable proper positioning and insertion of the workpiece into the die prior to the application of any deformation force or pressure to the workpiece. After the workpiece has been thus resiliently fitted into the die, as indicated in Fig. 3, the die cavity is then closed by continued advancement of the crosshead toward the anvil as shown in Fig. 4. Particular attention is directed to the fact that as the press crosshead moves from the position shown in Fig. 3 to that shown in Fig. 4, .the drive pin 45 and the head portion 47 remain relatively stationary and spring 53 is compressed permitting the disc 54 to engage solidly against the peripheral end shoulder of the drive pin head 47 as shown. In other words, the compressive strength of the spring 53 is substantially less than that required to effect any appreciable deformation of the workpiece within the die and punch bores.

With the disc 54 now in firm engagement with the head 47 of the drive pin and with the matrix cavity 17 completely closed, further movement of the press crosshead will cause the drive pin 45 to expel the end portion of the workpiece from the punch bore and in a single step, that is, with a continuous application of force above the elastic limit of the material forming the workpiece, the workpiece is transformed into a plastic state and so maintained from the commencement of deformation of the workpiece until it is completely formed. Particular attention is directed to the fact that the compressive strength of the spring 49 is such that from the instant that the planar face 43 of the punch 41 is brought into engagement with the matching face of the die, as shown in Fig. 4, it is firmly maintained in such relationship with respect to the die until after the blank is completely formed. In other words, the matrix die cavity is maintained closed throughout the entire period of deformation of the workpiece. In such manner and with the means shown and described, the entire blank is formed in a single stage of plastic flow. For this reason and in this manner, it is possible to effect a much greater displacement of metal than is possible with cold heading arrangements as have been heretofore developed. I

Moreover, in view of the fact that all of the upsetting occurs in a single stage, no intermediate work-hardening of the metal occurs so that I am able successfully to form blanks of different alloys, such as high alloy steel, which heretofore could not be successfully formed even in conventional two-blow header machines.

In Fig. 6, the drive pin is shown at the end of the compression stroke and in this position it is noted that the lower end of the drive pin projects through the punch 41 substantially to the outermost limit of the projecting bead 65. In Fig. 8 there is shown in perspective an enlarged view of a finished blank and from which it will be observed that the thin flashing 70 resulting from the curved edge 63 of the punch bore is recessed beneath the remainder of the upper surface 71 of the blank head and therefore is not objectionable, as would be thecase in the event that the flashing 70 projected above an otherwise flat surface of the head.

Simultaneously with the formation of the head upon the end of the blank, the lower extremity of the workpiece is caused to flow into the tapered end portion 19 of the die bore. The resultant tapered end formed on the blank is shown in Fig. 8 at 72. The taper formed on the shank end of the blank'may be slight or considerable depending on the shape of the die bore. If slight, a 'nice lead is formed on the blank that remains after the formation of threads on the blank. This lead end facilitates ready insertion of the shank end of a screw into a hole to speed up threading the screw in place. Or, the taper may It is to be understood, of course, that the formation ofthe tapered end on the blanks may not be desired, but this feature is pointed out as one possible of accomplishment through the use of the present invention. A further important feature of the present invention resides in the fact that the upper peripheral corners of a headed article, such as a hex headed screw, are automatically chamfered, as

well as the lower corners. Referring again to the view of Fig. 7 it will be observed that the metal will inherently resist completely filling the lower corners 73, as well as, the upper corners 74, of the enclosed matrix cavity. This' will leave the lower as well as the upper cornersof the' finally formed head slightly rounded or chamfered, which is to be desired. Of course, such chamfer of the lower edge is common with conventional cold heading processes and apparatus, but not at the upper edge. In conventional prior art processes where the matrix cavity is not closed,

until the end of the punch stroke and particularly where the machine is not set up properly, the metal will tend to,

flow out between the die and the punch to form a flashing therebetween. To eliminate such a flashing requires painstaking adjustment with repeated trial and error testing in setting up the machine and which is a major factor of expense in the operation of a conventional prior art machine.

Therefore, a further feature of the present invention resides in the ease and speed with which tools may be changed, or the machine set up. Only a simple liningup operation for centering the die and the punch is required and which may be' accomplished within a small fraction of the time heretofore necessary to place a machine in production. Due to closure of the matrix cavity before the commencement of material flow and maintaining such closure throughout the period of material flow, absolute control of the material is maintained. The formation of flashings around the periphery of'the heads is precluded as well as ofi-center heads. Accurately centered heads and absolute uniformity of all fin ished products are assured.

The advantages of the machine disclosed in Figsh-"l through 7 may be summarized by pointing out that the present invention has provided a machine capable of upsetting large volumes or masses of metal by application,

of a single blow, which heretofore has been possible only in double-blow machines. By the provision of a flared guide on the punch, the speed of operation of the machine can be substantially increased, because the in creased vibration of a piece of stock accompanying the increased machine speed does not interfere with it readily entering the punch bore and thereafter readily entering,

the die bore. By way of illustration only, it has been found that the speed of one machine, equipped with a punch unit of the present invention, could be increased from its previous normal speed of 350 blows per minute up to 525 blows per minute. By the provision of the annular bead, the flashing formed between the flared guide and the pressure pin will be recessed in a harmless place within a socket formed in the top of the head of the blank being formed. Also, simultaneously with the formation of the head, a reduced or tapered end is formed on the shank end of the blank to condition the blank to be formed into a gimlet end screw or into a screw having a nice lead.

The method of manufacture described herein is also. described and claimed in particular in my copending apf 7 plication, Serial"Number'460,223, filed concurrently herewith and entitled, Method of Upsetting' Wire 'Stock" and now abandoned.

,Having described the invention in what is considered tobe preferred embodiments thereof, it is desired that it be understood that the specific .details shown are merely illustrative and that the invention may be carried out inother ways.

I claim:

. l."In a cold heading press, the combinationcomprising a die having a face surface, a matrix cavity recessed in said surface, said cavity having a depth equal .to that of the head to be formed,a punch unit having a face surfacelfacing said die surface, said punch unit comprising a, main body member having an axial bore in coaxial alignment with said die cavity, said' bore having a diameter. less than. the diameter of said cavity,.said body member having a raised annular bead about said bore providing a flared extension of'said bore beyond the faeesufface of the remainder of said. body member, the opterdiameter of said bead being less than the diameter of said cavity, said bore being adapted cooperatively to receive the cndportion of a workpiece to be formed in said cavity, anda drive pin slidably arranged in said bore and being adapted to expel said workpiece end portion into said matrix cavity after the punch face surface has been moved into. abutting relation with the die face surface, the face of the drive pin in the extended position of the drive pin extending beyond thefface of the die but notbeyond the annular bead.

2. In a cold heading. press, the combination comprising a die having a planer'face surface, a matrix cavity recessed in said surface,, said cavity having a depth equal to that of the head to be formed, a punch unit comprising a main body member having a planar face surface of greater diameter than that of said cavity and adapted to be moved into parallel contacting relation with said die face surface, said body memberhaving an axialbore in coaxial alignment wi'th said die cavity and a diameter less, than the diameter of said cavity, and said body member having a raised annular bead about said bore providing an extension of said bore beyond said planar face surface of said body member, the outer diameter of said bead being less than the diameter of said cavity, said bore being adapted cooperativelyto receive the end portion of a workpiece to be'forrned in said cavity, theiouter end of said bore extension being slightly tapered outwardly to facilitate entry of said workpiece end portion into said bore, and a' drive pin slidably arranged in said bore and adapted to expel said workpiece end portion from said bore into said: matrix cavity when said planar punch surfaceis mov'edinto firm contacting engagement with said die surface surrounding said cavity, the end face of the drive pin being disposed between the face of the die and the face of the annular bead in the final position of the drive pin.

3. A punch unit for use in a cold'heading press provided with a die having a matrix cavity recessed in the face surface thereof, said cavity having/a depth equal to that of the head to be formed, saidpunch unit comprising a cylindrical body member adapted to be. mounted in the reciprocating press crosshead, said body member having an annular planar end surface portion and an axial boreextending therethrough, said bore being adapted cooperatively to receive the end portion of a workpiece to-be formed in said die cavity, a raised annular bead about the end of said bore and providing an extension therefor beyond said planar surface of said body membet, the external diameter of saidbead being less than the diameter of said cavity, the inner edge of said bead being rounded so as to facilitate entry of said workpiece into said bore, and a drivepin slidably arranged in said bore and adapted for driving said workpiece from said bore into said die cavity, the face of the drive pin in its extended position extending beyond the face of the die but not 'beyond' the annular bead.

4. A punch unityfor use in a cold heading press provided'with a die having a matrix'cavity recessed in the face surface thereof, said cavity having a depth equal to that of the head to be formed, said punch unit comprising a cylindrical body member adapted to be mounted in the reciprocating press crosshead, said body member having an annular planar surface portion and an axial bore extendingtherethrough, said bore being adapted cooperatively to receive the end portion of a workpiece who formed in said die'cavity, a raised annular bead about "the endof 'said' bore and providing an extension therefor beyond the planar surface of said body memher, the external diameter of said head being less than the diameter of said cavity, the inner edge of said head being-rounded so as tofaci'litate insertion of said workpiece into said bore, and a drive pin slidably arranged in said bore and adapted for driving said workpiece from'said bore into said'die cavity, the face of the drive pin in its extended position' extending beyond the face of the die but notbeyond'the annular bead, the radius of curvature of the inner edge of said bead being no greater than the outward extent of said bead from said planar surface.

5. In a cold heading machine, a die and a cooperating punch, said die being provided with a matrix cavity and a bore in the bottom of said cavity, said cavity having a depth equal to that of the head to be formed, said punch having a bore of the same diameter as said die bore and aligned therewith, transfer means operable to laterally'insert a workpiece into registry withsaid aligned-punch and die bores during separation of the punch and die'and retractable after the punch is moved sufficiently to cause insertion of an end of the workpiece-into the punch bore, said punch having its bore enlarged at the outer end thereof opposite the die to guide the end portion of a workpiece into the punch bore, pressure pin means movable in the punch bore and operable to apply an'upsetting force to said Workpiece end" portion, said punch having a continuous bead surrounding-said'outer'end of the punch bore to recess the flashing formed between the enlarged bore end and the pressure-pin means within the head of the blank being formedsaid' beadhaving an external diameter less than that of said cavity, the end face of said pressure pin means in its extended position'extending beyond the face of the die'but not beyondthe annular bead.

6. In a cold heading machine, a die having ahead defining cavity'recessed in the face surface thereof and an axial shank defining bore communicating with the bottom of said cavity, said'cavity having a depth equal to that of the head to be formed, a punch having a diameter greater than the diameter of said cavity and an axial bore aligned with said die bore, transfer means the stock, means for bringing the punch into engagement with the dieto completelyJclosc the die cavity and operable. torholdthe punch in firm engagement with the dieduring theentire period of upsetting of the stock, therpunch further having continuous bead surrounding said outer end of the punch bore to recess the flashing formedbetween the enlarged bore end and the pres.

sure pin means, within the head of the blank being formed said bead'having'an external diameter less than that of said cavity, the end face of said pressure pin means in its extended position extending beyond the face of the die but not beyond the annular bead.

7. In a cold heading press, the combination comprising a die having a face surface, a matrix cavity recessed in said surface, said cavity having a depth equal to that of the head to be formed, a punch unit including a main body member having a face surface facing said die surface, the face surface of said body member being larger than said matrix cavity so as to abut against said die face surface when said punch unit is moved toward said die, said main body member having an axial bore in coaxial alignment with said die cavity, said bore having a diameter less than the diameter of said cavity, a raised annular bead about said bore and carried by said body member in fixed relation thereto, said bead providing a flared extension of said bore beyond the face surface of the remainder of said body member so as to readily guide a workpiece into said bore, the outer diameter of said bead being less than the diameter of said cavity at the place occupied by said bead so that said bead is spaced from the walls of said cavity to provide for the flow of metal around said bead and between the outer surface of said bead and the opposed surfaces 10 of the walls of the matrix cavity, and a drive pin slidably arranged in said bore to force said workpiece toward said matrix cavity to fil-l the unoccupied portions of said cavity and form a head on said workpiece, the end face of the drive pin being disposed substantially beyond the face of the die in the final position of the drive pin.

References Cited in the file of this patent UNITED STATES PATENTS 578,437 Allen Mar. 9, 1897 1,146,145 Ferry July 13, 1915 1,501,081 Wilcox July 15, 1924 1,561,863 Kuhne Nov. 17, 1925 1,646,425 Simpson Oct. 25, 1927 1,690,419 McCain Nov. 6, 1928 1,891,521 Brackett Dec. 20, 1932 1,892,030 Anderson Dec. 27, 1932 1,921,654 Burbank Aug. -8, 1933 2,331,324 Jakosky Oct. 12, 1943 FOREIGN PATENTS 834,233 France Nov. 16, 1938 

